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Sulcus (neuroanatomy)
and sulcus.]] Fig. 726– Lateral surface of left cerebral hemisphere, viewed from the side.]] Fig. 727 - Medial surface of left cerebral hemisphere.]] In neuroanatomy, a sulcus (Latin: "furrow", pl. sulci) is a depression or fissure in the surface of the brain. It surrounds the gyri, creating the characteristic appearance of the brain in humans and other large mammals. Large furrows (sulci) that divide the brain into lobes are often called fissures. The large furrow that divides the two hemispheres—the interhemispheric fissure—is very rarely called a "sulcus". Individual variation The sulcal pattern varies between human individuals, and the most elaborate overview on this variation is probably an atlas by Ono, Kubick and Abernathey: Atlas of the Cerebral Sulci.Ono, Kubick, Abernathey, Atlas of the Cerebral Sulci, Thieme Medical Publishers, 1990. ISBN 0-86577-362-9. ISBN 3-13-732101-8. Some of the larger sulci are, however, seen across individuals - and even species - so it is possible to establish a nomenclature. Gyrification across species The variation in the amount of fissures in the brain (gyrification) between species is related to the size of the animal and the size of the brain. Mammals that have smooth-surfaced or nonconvoluted brains are called lissencephalics and those that have folded or convoluted brains gyrencephalics.Hofman MA. (1985). Size and shape of the cerebral cortex in mammals. I. The cortical surface. Brain Behav Evol. 27(1):28-40. PMID 3836731Hofman MA. (1989).On the evolution and geometry of the brain in mammals. Prog Neurobiol.32(2):137-58. PMID 2645619 The division between the two groups occurs when cortical surface area is about 10 cm2 and the brain has a volume of 3–4 cm3. Large rodents such as beavers ( ) and capybaras ( ) are gyrencephalic and smaller rodents such as rats and mice lissencephalic.Martin I. Sereno, Roger B. H. Tootell, "From Monkeys to humans: what do we now know about brain homologies," Current Opinion in Neurobiology 15:135-144, (2005). Brain development In humans, cerebral convolutions appear at about 5 months and take at least into the first year after birth to fully develop. Caviness VS Jr. (1975). Mechanical model of brain convolutional development. Science. 189(4196):18-21. PMID 1135626 It has been found that the width of cortical sulci not only increases with age Tao Liu, Wei Wen, Wanlin Zhu, Julian Trollor, Simone Reppermund, John Crawford, Jesse S Jin, Suhuai Luo, Henry Brodaty, Perminder Sachdev (2010) The effects of age and sex on cortical sulci in the elderly. Neuroimage 51:1. 19-27 May. PMID 20156569, but also with cognitive decline in the elderly. Tao Liu, Wei Wen, Wanlin Zhu, Nicole A Kochan, Julian N Trollor, Simone Reppermund, Jesse S Jin, Suhuai Luo, Henry Brodaty, Perminder S Sachdev (2011) The relationship between cortical sulcal variability and cognitive performance in the elderly. Neuroimage 56:3. 865-873 Jun. PMID 21397704 Notable sulci * Calcarine sulcus * Central sulcus * Central sulcus of insula * Cingulate sulcus * Circular sulcus of insula * Collateral sulcus * Fimbrodentate sulcus * Hippocampal sulcus * Inferior frontal sulcus * Inferior temporal sulcus * Intermammary sulcus * Intraparietal sulcus * Lateral sulcus * Lunate sulcus * Occipitotemporal sulcus * Olfactory sulcus * Paracentral sulcus * Parieto-occipital sulcus * Postcentral sulcus * Precentral sulcus * Rhinal sulcus * Subparietal sulcus * Sulcus of corpus callosum * Superior frontal sulcus * Superior temporal sulcus * Transverse occipital sulcus * Transverse temporal sulcus Macaque A macaque has a more simple sulcal pattern. In a monograph Bonin and Bailey list the following as the primary sulciGerhardt von Bonin, Percival Bailey, The Neocortex of Macaca Mulatta, The University of Illinois Press, Urbana, Illinois, 1947: * Calcarine fissure (ca) * Central sulcus (ce) * Sulcus cinguli (ci) * Hippocampal fissure (h) * Sulcus intraparitalis (ip) * Lateral fissure (or Sylvian fissure) (la) * Sulcus olfactorius (olf) * Medial parieto-occipital fissure (pom) * fissura rhinalis (rh) * Sulcus temporalis superior (ts) - this sulcus runs parallel to the lateral fissure and extends to the temporal pole and often superficially merges with it. See also * Sulcus (anatomy) References External links *Visual explanation of gyri, sulci, and fissures Category:Neuroanatomy *